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TDI Standards and Procedures Part 2: TDI Diver Standards

31. Air Diluent Closed Circuit Procedures Diver, Unit Specific-

31.1 Introduction This is the second level certification course for divers wishing to utilize a closed circuit rebreather (CCR) for air diving. The objective of the course is to train divers in the benefits, and proper procedures for diving a CCR and to develop basic CCR diving skills to a maximum depth of 40 metres / 130 feet using an air diluent for formal decompression diving.

31.2 Qualifications of Graduates Upon successful completion of this course, graduates may engage in decompression diving activities utilizing a CCR without direct supervision provided: 1. The diving activities approximate those of training 2. The areas of activities approximate those of training 3. Environmental conditions approximate those of training Upon successful completion of this course, graduates are qualified to enroll in: 1. TDI Mixed Gas CCR unit specific course 2. TDI Advanced Wreck Course

31.3 Who May Teach An active TDI Instructor with a TDI Air Diluent CCR Decompression Procedures Instructor rating for the specific unit being used.

31.4 Student to Instructor Ratio Academic 1. Unlimited, so long as adequate facility, supplies and time are provided to ensure comprehensive and complete training of subject matter Confined Water (swimming pool-like conditions) 1. A maximum of 3 students per active TDI Instructor is allowed. One additional student may be added if they are doing a refresher or unit crossover.

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Open Water (ocean, lake, quarry, spring, river or estuary) 1. A maximum of 3 students per active TDI Instructor is allowed. One additional student may be added if they are doing a refresher or unit crossover. 2. The ratio should be reduced as required due to environmental or operational constraints

31.5 Student Prerequisites 1. Minimum age 18 2. Provide proof of 50 logged dives. If completing a unit crossover, at least 10 logged CCR dives in the last 12 months. 3. Provide proof of TDI Advanced Diver and Deco Procedures Diver or equivalent from agencies recognized by TDI 4. If the rebreather is a TDI approved sidemount rebreather, the student must hold the TDI Sidemount or equivalent, provide proof of 10 logged sidemount dives, and any additional requirements the sidemount rebreather manufacturer may have. OR 1. Minimum age 18 2. TDI Air Diluent CCR Diver certified or equivalent, 3. Minimum of 30 hours and 30 dives on the CCR unit. 4. Six months CCR diving experience

31.6 Course Structure and Duration Confined Water Execution 1. Minimum of 60 minutes confined water training to a maximum of 9 metres / 30 feet Open Water Execution 1. Equipment configuration session, confined water session, and 50 metre fully-equipped CCR diver surface tow must be completed prior to open water training dives 2. Minimum of 420 minutes open water training, to be completed over a minimum of 7 dives with a gradual increase in depth each day to a maximum of 40 metres / 130 feet

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Course Structure 1. TDI allows instructors to structure courses according to the number of students participating and their skill level 2. The final exam may be given orally if not available in a language the student understands Duration 1. Minimum of 6 hours academic development and 2 hours equipment maintenance workshop 2. The duration of the entire course must take a minimum of 5 days Crossover 1. If a student already qualified as TDI Air Diluent CCR Deco Procedures Diver or equivalent from an agency recognized by TDI and wishes to qualify on another CCR recognized by TDI, the student must follow all unit specific course standards with the exception of: a. Minimum of 60 minutes confined water training to a maximum of 9 metres / 30 feet b. Minimum of 240 minutes open water training to be completed over a minimum of 4 dives to a maximum of 40 metres / 130 feet , with two dives deeper than 30 metres/100 ft. 2. If a student already is qualified as a TDI Kiss Spirit air diluent decompression diver or equivalent and is crossing over to the Sidewinder, the student must complete an academic session covering unit build, hose routing, donning and doffing, and a minimum of 180 minutes open water training over a minimum of 3 dives. Upgrades 1. If a student has the TDI Air Diluent certification and wishes to do the decompression part of this course, only 240 minutes in open water is required. Students will complete a skills evaluation dive plus a minimum of 4 open water dives with 2 dives deeper than 30 meters/100 feet. 2. The student must have a minimum of 30 logged hours over 30 dives before enrollment on the deco course 3. Six months CCR diving experience

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31.7 Administrative Requirements Administrative Tasks: 1. Collect the course fees from all the students 2. Ensure that the students have the required equipment 3. Communicate the schedule to the students 4. Have the students complete the: a. TDI Liability Release and Express Assumption of Risk Form b. TDI Medical Statement Form Upon successful completion of the course the instructor must: 1. Download and retain student’s dive logs of all training dives. 2. Issue the appropriate TDI certification by submitting the TDI Diver Registration Form to TDI Headquarters or registering the students online through member’s area of the TDI website

31.8 Training Materials Required materials: 1. TDI Diving Student Manual or eLearning 2. TDI Diving Rebreathers Instructor Guide 3. Manufacturer’s manual and updates 4. TDI Decompression Procedures Student Manual or eLearning 5. TDI Advanced Nitrox Student Manual or eLearning 6. Manufacturer’s Build 7. Manufacturer's minimum training standards 8. TDI CCR Preflight Checklist 9. Rebreather course evaluation form (see appendix) Optional: 1. TDI Diving Rebreathers PowerPoint Presentation 2. Mel Clark- Rebreathers Simplified 3. Skills prompt slates

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31.9 Required Equipment The following equipment is required: 1. A complete closed circuit rebreather . Any modifications to the unit must be approved by the manufacturer 2. Minimum of 1 CCR and 1 backup OC/CCR computer for bailout in event of system failure 3. Mask, fins and a suitable line-cutting device 4. Slate and pencil 5. Reel with a minimum of 50 metres / 165 feet of line 6. Lift bag / delayed (DSMB) with adequate lift and size for the dive environmentand a backup. Required for open water environments only. 7. Exposure suit appropriate for the open water environment where training will be conducted 8. Access to an analyzer 9. Appropriate 10. Bailout gas supply cylinder with a minimum capacity of 5.7 litres / 40 cu ft air or nitrox may be used Note: The instructor and any certified assistant will also carry a bailout gas supply during all open water sessions. This redundant gas source must be greater than the instructor and any certified assistant’s bailout requirements.

31.10 Required Subject Areas The TDI Diving Rebreathers Student Manual or eLearning and the manufacturer’s manual are mandatory for use during this course but instructors may use any additional text or materials that they feel help present these topics. The following topics must be covered during the course. 1. History and Evolution of Rebreathers 2. Comparison of Open Circuit, Closed Circuit and Semi Closed Circuit Rebreather Systems and the Benefits/Problems with Each 3. Practical Mechanics of the System a. Assembly and disassembly of the unit b. Layout and design of the unit c. Absorbent canister design and maintenance d. Proper packing of canister, in accordance with manufacturer’s recommendations

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e. loop de-contamination procedures f. Manufacturer supported additional items (Bailout valve, Automatic Diluent Valve, etc) g. Loop volume – minimum/optimum 4. Gas Physiology a. Oxygen (O2) risks: , Toxicity, b. absorption c. (CO2) toxicity, d. Gas consumption 5. Electronic and Manual Systems Design and Maintenance a. Oxygen (O₂) metabolizing calculations b. Fuel cells i. Maintenance ii. Replacement iii. Manufacturing date c. System electronics functionality and calibration procedures 6. Dive Tables a. Constant partial of oxygen (PPO₂) theory b. Central nervous system (CNS) and awareness of oxygen tracking units (OTU) 7. Dive Computers a. Mix adjustable b. Constant percentage of oxygen (PO₂) c. Oxygen (O₂) integrated d. Decompression conservatism/Gradient factor selection 8. a. Operational planning b. Gas requirements including bailout scenarios c. Scrubber duration d. Oxygen limitations e. Nitrogen limitations 9. Emergency Procedures a. Use of B.A.D.-D.A.S. - Bail out, Anxiety breaths, Decide – Diluent flush, Always know your PO2, Skills to overcome problem b. Three H’s problems c. Flooded loop d. Cell warnings e. Battery warnings and electronic failures f. Bailout gas requirements

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31.11 Required Skill Performance and Graduation Requirements All standards set by both TDI and the rebreather manufacturer must be met, while maximum limits of neither may be exceeded. The following open water skills must be completed by the student during open water dives with the following course limits: 1. All skills must be demonstrated by the instructor on the unit-specific CCR 2. All open water dives must be between 9 metres / 30 feet to 40 metres / 130 feet 3. Two dives must be deeper than 20 metres / 66 feet and two dives must be deeper than 30metres / 100 feet 4. Satisfactorily complete any additional skills required by the unit specific manufacturer. 5. PO₂ not to exceed manufacturer’s recommendation or a working limit of 1.3 bar 6. All dives to be completed within CNS percent limits with a recommend maximum of 80 percent of the total PO₂ CNS limit 7. Safety stops to be conducted with a minimum 3 minutes at 6 metres / 20 feet 8. When the user opts for an automatic diluent valve (ADV) fitted by the manufacturer, additional skills such as regular diluent gauge monitoring and addition control must be emphasized 9. Calculate deep bailout gas at 45.30 litres / 1.6 cubic feet per minute usage and at 30 liters/1.1 cubic feet per minute if a separate deco gas is carried 10. All dives to be completed within appropriate constant PO₂ decompression tables 11. Student is only certified for decompression diving on the specific CCR unit 12. Students must do one bailout from depth on open circuit to include simulated or actual decompression Open Water Skills: 1. Pre dive checks a. Unit build-up b. Scrubber packing c. Positive and negative checks 2. Verify diluent and O₂ cylinder contents using O₂ analyzer 3. Demonstrate correct pre dive planning procedures including

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a. Limits based on system performance b. Limits based on oxygen exposures at chosen PPO₂ levels c. Limits based on nitrogen absorption at planned depth and PO₂ setpoint d. Appropriate selection of decompression conservatism/gradient factors for planned dive e. Thermal constraints 4. Emergency procedures a. Mouthpiece familiarity drills b. Bailout drills c. Gas shutdowns and loss of gas d. Broken hoses e. Flooded absorbent canister f. Carbon dioxide (CO₂) breakthrough g. Semi-closed mode h. Low oxygen drills i. High oxygen drills j. Flooding loop k. Electronics and battery failure l. Properly execute the ascent procedures for an incapacitated CCR diver and tow a minimum of 50 metres at the surface with both rescuer and victim wearing complete CCR diving system and bailout system. 5. Use of BCD/suit and effective management of loop breathing volume for control 6. Stop at 3-6 metres / 10 – 20 feet on descent for leak bubble check 7. Electronics systems monitoring for PO₂ levels (SETPOINT) and switching setpoints 8. Manual control of setpoint if electronically controlled CCR is not used 9. Use and adjustment of Heads Up Displays and computers 10. Mask removal and replacement 11. Use of lift bag / delayed surface marker buoy and reel 12. Proper execution of the dive within all pre-determined dive limits 13. Constant loop volume management 14. Cell validation checks with appropriate use of diluent and oxygen 15. Post dive clean of unit to avoid contamination and spread of disease

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If this is the first CCR course taken on the unit the following must be included: 1. Post dive clean of unit a. Mouth piece and hoses b. Clean and disinfect unit c. Inspect components of unit 2. Dive maintenance of unit a. Cell remove and replace b. Mouth piece strip and rebuild c. Replacing/recharging batteries Decompression related in water skills: 1. Demonstrate comfort swimming on surface and at depth carrying 1 bailout/ decompression cylinder 2. Demonstrate ability to drop and retrieve 1 bailout/decompression cylinder while maintaining position in the water column 3. Demonstrate ability to deploy SMB or lift-bag solo and as a member of a team 4. Demonstrate appropriate reaction to gas hemorrhage from manifold or first stage, SPG and primary regulator 5. Demonstrate appropriate reaction to simulated free-flowing deco regulator 6. deco gas for at least 1 minute 7. Oxygen rebreather mode at less than 6 metres / 20 foot stop 8. Complete 1 bailout scenario at depth to include simulated or actual decompression obligation on open circuit In order to complete the course and achieve the TDI Air Diluent Decompression Procedures CCR rating the student must: 1. Satisfactorily complete the written examination with a minimum score of 80 percent and 100% remediation 2. Complete to the instructor’s satisfaction all confined and open water skill development sessions 3. Demonstrate mature, sound judgment concerning dive planning and execution 4. Course must be completed within 6 weeks from the starting date 5. Complete a refresher course following a period of inactivity greater than 6 months following the course Recommended Additional Reading and Support Material 1. - A Learners Guide to Closed Circuit Rebreather Operations 2. Kenneth Donald - Oxygen & The Diver 3. John Lamb - Oxygen Measurement for Divers 4. Barsky, Thurlow & Ward - The Simple Guide to 5. Bob Cole - Rebreather Diving 6. Jeffrey Bozanic - Mastering Rebreathers

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